Matthew has already killed 15 people and carved a trail of destruction in several Caribbean countries.

As of Wednesday night, Matthew hurled 115 mph winds as it passed over the Bahamas, the National Hurricane Center said.

The hurricane was about 170 miles south of Nassau, Bahamas, and 360 miles from West Palm Beach, Fla.

President Barack Obama warned Americans in the storm's path to pay attention and take any evacuation orders seriously. He said if the core of the storm strikes Florida, it could have a "devastating effect."

Florida braces for 'direct hit'

Scott has activated 1,500 National Guard members. He has repeatedly warned that a direct hit by Matthew could lead to "massive destruction" on a level unseen since Hurricane Andrew devastated the Miami area in 1992.

Many residents found long gas lines Wednesday, but Scott said the state is not experiencing any gas supply or distribution shortages.

"We have heard of some individual stations (being) short, but in no area of the state are we short of fuel," the governor said, adding the state has placed fuel in some areas and sends it to stations that need more.

Airline passengers were urged to call before leaving for the airport. Fort Lauderdale's airport is to close Thursday at 10:30 a.m. and FlightAware.com says almost 250 flights are canceled at Miami International Airport.

State offices will be closed Thursday and Friday in 26 counties, Scott said.

In Jupiter, resident Randy Jordan told WPEC people were pushing and shoving their way through the local Home Depot to buy supplies ranging from batteries to flashlights.

Mandatory evacuations in South Carolina

South Carolina Gov. Nikki Haley gave evacuation orders for the coastal counties of Charleston and Beaufort.

An estimated 250,000 residents evacuated from Charleston and Beaufort, said Kim Stenson, the director of South Carolina Emergency Management. He said as many as 200,000 people will leave Thursday.

Tempers apparently flared during the slow traffic out of Charleston. A man got out of his truck at point where vehicles were being redirected, removed a traffic cone and sped away.

Police chased the man until he stopped on a dead-end road. Berkeley County Chief Deputy Mike Cochran said the man fired at deputies and police officers, who shot back and wounded the man.

The man was hospitalized, but his condition is unknown.

The South Carolina Department of Transportation changed the directions of eastbound traffic lanes to accommodate the exodus of people leaving coastal cities like Charleston.

North Carolina playing it by ear

North Carolina Gov. Pat McCrory declared a state of emergency for more than half the state's 100 counties. The changing forecast now predicts the storm won't have as great an impact on the state as once feared, and Matthew might even turn around before it gets to North Carolina.

"We're just going to have to play it by ear and have our resources ready," the governor said.

Officials are still concerned areas in eastern North Carolina that were recently flooded will see drenching rains from Matthew.

Georgia governor: 'Remain calm, be prepared'

Georgia Gov. Nathan Deal has declared a state of emergency in 30 counties on or near the Atlantic Coast.

"I urge Georgians in the affected areas to remain calm, be prepared and make informed, responsible decisions as we continue to monitor Hurricane Matthew's path," Deal said.

Residents of islands just east of Savannah were being urged to evacuate. A mandatory order was in effect in Tybee Island.